In the dental field, vacuum assemblies including related conduit and tubing are used to remove saliva together with particulate material or debris in the oral cavity of one undergoing various dental procedures. Many devices have been manufactured for insertion into the oral cavity to provide the means for saliva withdrawal under vacuum, which minimizes complete stoppage of flow in the conduit or tubing to the source of a suction side of a pump, since stoppage may result in tissue being drawn into the orifice or orifices of such devices and to thereby arrest fluid flow to the extent that damage results to the tissue drawn into such orifice and orifices.
Various devices and in particular, vacuum relief valves, such as spring loaded ball valves, guided poppet valves and the like have been utilized in vacuum assemblies to obviate the problem of fluid flow stoppage and tissue damage. However, any such vacuum valve assemblies overreact with concomitant fluid flow irregularities and vacuum (pressure) oscillations in the vacuum line resulting in possible tissue damage and failure to maintain optimum levels of vacuum, i.e. generally about 10.+-.2 inches of mercury.